Hakima

September 25, 2018

The Concept
The Hakima is a light-sport, multi-rotor aircraft concept that would allow a new generation of pilots to safely experience flying at low speed and very low altitudes for 20 minutes at a time.

The Background
The idea for the Hakima hoverbike came from the FlytCycle prototype created by Ansel Misfeldt of Flyt Aerospace. Many inventors like Ansel are currently on working electric hoverbikes, and these inventions could lead to a new type of flying powersport vehicles.
Ansel and his team have a whole database on motors / props / ESCs of varying sizes and have lots of experience with how these systems need to be designed. He helped us put some numbers on what would be required to make the Hakima fly.

How It Works
The Hakima is powered by 8 fans composed of two contra-rotating blades with a total diameter of 70 centimeters each. The Hakima’s 16 kw battery pack is composed of multiple cells, and it measures 20 cm x 20 cm x 75 cm in size.
The first goal is to keep the vehicle’s weight and payload to 60% of the maximum thrust available. In a coaxial configuration, the lower prop is ~20% less efficient than the top one, which means there is a small reduction in efficiency, and the props will also require quite a bit of excess thrust to stabilize themselves out of the ground effect.

The Hakimas’s 70-cm blades can only handle a maximum thrust of 57lbs before reaching their design limits. This means that with 16 props, the Hakima will generate 820lbs of maximum thrust with its coaxial blades.

820 lbs max thrust at 60% max load equals a maximum useful takeoff weight of 492 lb. If we assume the pilot weights a maximum of 180lbs, that leaves 312 lbs for the frame, controls, and batteries.

This might sound like a lot of weight to carry, but the airframe and motors will easily weigh 100lbs even if they are made of carbon fiber. The goal is to keep the total weight to 254 or below so the Hakima can qualify as an ultralight aircraft.

Being optimistic, we can assume it would be feasible to fit 150lbs of batteries on the Hakima. The best ‘off the shelf’ batteries we know for that weight are 16.2kW. You generally want to keep them from going below 20% charge or they degrade much faster, so that gives you approximately 13kW of useful energy.

The propellers at hover, assuming no ground effect and a 180-lb pilot, will need ~2.5kW directly. If we assume an 80% efficiency, which matches well with real world flight data, which translates to 3.1kW for each propeller, for a system total of 49.5kW.

So the 13kW of useful of energy will last approximately 16 minutes. This is the shortest time you would expect, as a lighter pilot would be able to fly for longer.

To control the roll, pitch, yaw, and altitude, the pilot will use controls similar to a helicopter: cyclic and collective. These controls will be linked to the smart flight module, which will adjust each propeller’s speed to create the desired effect. The Hakima could also be equipped with other features to modify the airflow; and these will depend on the many tests required to optimize the aircraft’s final configuration.

What It’s Used For
The Hakima would be used purely as a recreational aircraft. With its ability to fly anywhere at low speed and low altitude, this new kind of flying kart will make it possible to explore the backcountry and experience the joy of flight.

I would like to thank Ansel Misfeldt for sharing his knowledge and expertise with me. Ansel is currently working on building new prototypes similar to the Hakima and you can contact him at Flyt Aerospace to learn more about his plans.

I would also like to thank Martin Rico for creating the images of the Hakima concept. Martin studied Design at the University of Buenos Aires and now works as an Industrial Designer for the ICAO NGAP initiative.